SU1442911A1 - Method of analysing acetone - Google Patents

Abstract

This invention relates to analytical chemistry, in particular, to the determination of acetone in leaching and chemical waters. The goal is to improve the accuracy of the method. The determination is carried out by treating the analyzed sample with an excess of hydroxyl hydroxylamine hydroxylamine hydroxylamine (the obtained compound is treated with a 1.2-6 fold excess of potassium hydroxide or sodium with respect to the formed HCI, followed by titration of excess alkalinity of HC1 in the presence of bromine-phenol blue O) It is characterized by high accuracy, good convergence of parallel definitions and reproducibility of results. 1 Table C

Description

The invention relates to analytical chemistry, in particular, methods for the quantitative determination of acetone, and can be used to determine the concentration of acetone in washing and chemical contaminated waters, the acetone regenerator, as well as polymerization in the solution method of polymer synthesis.

The purpose of the invention is to improve the accuracy of the method.

The method is carried out according to the following procedure.

An apiquot of the analyzed sample containing from 4 to 20 mg / eq of acetone is introduced into the flask, 50 cm of distilled water is added and stirred, and 15 cm of a 20% hydroxylamine hydrochloride solution (40 mg / eq) are added. ), stopper, mix and incubate for 5 minutes. Then 25 cm of 1 mol / dm solution of potassium hydroxide or sodium (25 mg / eq.), 6-8 drops of bromophenol blue indicator were injected into the flask and titrated with 0.5 mol / dm of hydrochloric acid until a greenish yellow color appeared.

In parallel under the conditions of analysis

Titration of the blank run is performed. . The concentration of acetone in the analyzed sample (X),%, calculated by the formula

(V -.U.) -N 58.08-100

ga tooo

V is the volume of hydrochloric acid solution consumed by titanium;

l

sampling, cm; V is the volume of hydrochloric acid solution consumed per

titration of idle experience, cm;

58.08 molar mass equivalent;

g / mol;

m is the mass of an aliquot of the sample being analyzed, g / cm,

Example 1. Determination of acetone concentration in acetone regenerate (the concentration of acetone, determined ohtographically, is equal to 92.3%).

In a flask containing 50 cm of distilled water, add 1 cm of sample (12 mg / eq.), 15 cm of a 20% strength solution of hydroxylamine (three times excess), mix and incubate for 5 minutes. Then add 0

5 0 5

0

five

0

five

g

25 cm of 1 mol / dm3 solution of potassium hydroxide or sodium (two-fold excess with respect to hydrochloric acid), 6-8 drops of the indicator and titrated with 0.5 mol / dm of hydrochloric acid until a greenish-yellow color appears.

In parallel, under the conditions of the analysis, a blank experiment was carried out. The concentration of acetone was calculated using the above formula. The results of parallel determinations are 92.3; 92.7; 92.1%.

Example 2: Determination of acetone concentration in wash water (concentration equal to 11.6%).

The determination is carried out according to the procedure of Example 1. 10 cm samples (20 mg / eq) are taken for analysis. The excess of hydroxylamine is 2, the excess of potassium hydroxide or sodium is 1.2.

The results of parallel determinations are 11.6; 11.5; 11.6%.

Example 3 Determination of acetone concentration in chemical contaminated water (concentration equal to 1.2%).

The determination is carried out according to the procedure of Example 1. A 20 cm sample is taken for analysis (4 mg / eq). The excess of hydroxylamine is 10, the excess of potassium hydroxide or sodium is 6.

The results of parallel determinations are −1.19; 1.21; 1.28%.

Example 4: Determination of the concentration of acetone in the polymerizate (concentration equal to 25.0%).

The determination is carried out according to the method of Example 1.

About 2.5 g of the sample (10 mg eq.) Is placed in a suspended flask. The excess of hydroxylamine is 4, the excess of potassium or sodium hydroxide is 2.5.,

The results of parallel determinations are 24.8; 25.0; 21.1%.

Example 5 (control), Determination of the concentration of acetone in the polymer (concentration equal to 25.8%).

The determination is carried out according to the method of Example 1.

About 4 g of sample (18 mg / eq) is placed in the flask. 15 cm of hydroxylamine hydrochloride solution (an excess of 2.2), 20 cm of potassium hydroxide or sodium hydroxide (an excess of 1.1) are added.

The results of parallel determinations are 25.3; 24.8; 24,.)%.

31

PRI me R 6 (control). Determination of the concentration of acetone in chemical zagred water (concentration equal to 1, 35%).

The determination is carried out according to the procedure of Example 1. 20 cm (4.6 g / eq) samples are taken for analysis. 15 cm of hydroxylamine hydrochloride solution (an excess of 8.7) and 30 cm of potassium hydroxide or sodium (an excess of 6, five).

The results of parallel determinations are 1.38; 1.30; 1.27%.

PRI me R 7 (control by a known method). Determination of acetone concentration in the wash water (concentration 14.2%).

A 2 cm sample (0.5 mg / eq) and a 10 cm semi-neutralized alcohol solution of hydroxylamine (CNH OHHCl 0.4 mol / dm, which is obtained by mixing solutions of hydroxylamine hydrochloride and potassium hydroxide in a mole ratio of 2: 1, and incubated for 30 minutes Then titrated with a 0.1 mol / dm solution of hydrochloric acid in the presence of bromophenol blue to a yellow color

one

In parallel, under the conditions of analysis, a blank experiment was carried out. The concentration of acetone calculated by the formula

(YlYiL 400

The results of parallel determinations are 24.1; 23.3, 22.6%, i.e. in this case, there is an underestimation of the analysis results and a large scatter of parallel determinations.

The table shows the metrological characteristics of the known and proposed methods for determining acetone.

20

25

ra.

In parallel, under the conditions of analysis, a blank experiment was carried out.

The concentration of acetone is calculated according to the above formula.

The determinations were carried out immediately after preparation of the reagent and after three days. In the first case, the results of parallel determinations are 14.4; 13.8; 13.6%, in the second 13.6; 12.6; 12.8%.

In this case, there is a large scatter of parallel definitions and even an understatement of the results in the second case.

PRI me R 8 (control according to a known method). Determination of the concentration of acetone in the polymer (concentration equal to 25.0%).

About 3 g (mg / eq.) Of the sample, 75 cm of distilled water were introduced into the flask and stirred for 2 minutes. Then 15 cm of a 20% hydroxylamine hydrochloride solution (excess 3) were introduced into the flask, incubated for 5 min and titrated with 1 mol / dm solution of alkali in the presence of an indicator of bromophenol blue to blue-violet color solution.

thirty

31-60 61-98

0.11 0.21

0.9 0.9

Thus, as can be seen from the examples given, the proposed method has several advantages over the well-known one: it is characterized by high accuracy, good convergence of parallel definitions and reproducibility of results.

Claims (1)

Invention Formula A method for determining acetone by treating an analyzed sample with an excess of an oxymeth reagent and titrating excess alkalinity with hydrochloric acid in the presence of bromophenol blue, characterized in that, in order to improve the accuracy of the method, the resulting compound is treated with a 1-2-6 fold excess —Comm potassium or sodium hydroxide with respect to the hydrochloric acid formed and hydroxylamine hydrochloride is used as an oxidizing reagent.